The objectives of the present study are: a. to isolate and characterize the binding protein for tetracycline transport in Staphylococcus aureus, and b. To isolate and characterize the tetracycline resistance protein from S. aureus. Either equilibrium dialysis or acrylamide gel electrophoresis will be used to monitor the binding protein. General methods of protein fractionation will be developed for the isolation of the protein. An attempt will be made to specifically label the resistance protein by induction in the presence of naldixic acid and H3-leucine. If this approach is not successful, then the new proteins which are formed on induction will be visualized by acrylamide gel electrophoresis. The proteins will be isolated using the general methods for protein fractionation. The possible interaction of the binding protein and the resistance protein will be determined in an effort to delineate the role of the latter protein in the resistant cell. The binding properties of the transport protein and the resistance protein for a wide variety of tetracyclines will be evaluated. These data should clarify the role these respective proteins play in the in vivo antibacterial activity of the tetracycline antibiotic.